U.S. Pat. No. 3,826,730 describes an electrochemical sensing probe for determining oxygen concentration. This probe includes a membrane 52 held against an end of an electrode 54 by a cap 50. There have been problems insuring uniform pressure of such membrane against the electrode. If too much pressure is exerted, it is difficult for the electrolyte to reach the electrode. Conversely, if not enough pressure is exerted, electrolyte will build up at the electrode face causing excessively long response time of the probe.
In addition to the above mentioned reference, another sensing probe is described in my co-pending patent application entitled "Electrochemical Sensing Probe," filed Dec. 19, 1978, Ser. No. 970,890, which illustrates at the membrane-electrode contact area the general problem described above.